Goto Section: 73.186 | 73.189 | Table of Contents
FCC 73.187
Revised as of October 1, 2011
Goto Year:2010 |
2012
§ 73.187 Limitation on daytime radiation.
(a)(1) Except as otherwise provided in paragraphs (a)(2) and (3) of
this section, no authorization will be granted for a Class B or Class D
station on a frequency specified in § 73.25 if the proposed operation
would radiate during the period of critical hours (the two hours after
local sunrise and the two hours before local sunset) toward any point
on the 0.1 mV/m contour of a co-channel U.S. Class A station, at or
below the pertinent vertical angle determined from Curve 2 of Figure 6a
of § 73.190, values in excess of those obtained as provided in
paragraph (b) of this section.
(2) The limitation set forth in paragraph (a)(1) of this section shall
not apply in the following cases:
(i) Any Class B or Class D operation authorized before November 30,
1959; or
(ii) For Class B and Class D stations authorized before November 30,
1959, subsequent changes of facilities which do not involve a change in
frequency, an increase in radiation toward any point on the 0.1 mV/m
contour of a co-channel U.S. Class A station, or the move of
transmitter site materially closer to the 0.1 mV/m contour of such
Class A station.
(3) A Class B or Class D station authorized before November 30, 1959,
and subsequently authorized to increase daytime radiation in any
direction toward the 0.1 mV/m contour of a co-channel U.S. Class A
station (without a change in frequency or a move of transmitter site
materially closer to such contour), may not, during the two hours after
local sunrise or the two hours before local sunset, radiate in such
directions a value exceeding the higher of:
(i) The value radiated in such directions with facilities last
authorized before November 30, 1959, or
(ii) The limitation specified in paragraph (a)(1) of this section.
(b) To obtain the maximum permissible radiation for a Class B or Class
D station on a given frequency from 640 through 990 kHz, multiply the
radiation value obtained for the given distance and azimuth from the
500 kHz chart (Figure 9 of § 73.190) by the appropriate interpolation
factor shown in the K[500]column of paragraph (c) of this section; and
multiply the radiation value obtained for the given distance and
azimuth from the 1000 kHz chart (Figure 10 of § 73.190) by the
appropriate interpolation factor shown in the K[1000]column of
paragraph (c) of this section. Add the two products thus obtained; the
result is the maximum radiation value applicable to the Class B or
Class D station in the pertinent directions. For frequencies from 1010
to 1580 kHz, obtain in a similar manner the proper radiation values
from the 1000 and 1600 kHz charts (Figures 10 and 11 of § 73.190),
multiply each of these values by the appropriate interpolation factors
in the K'[1000]and K'[1600]columns in paragraph (c) of this section,
and add the products.
(c) Interpolation factors. (1) Frequencies below 1000 kHz.
fkHz K^500 K^1000
640 0.720 0.280
650 0.700 0.300
660 0.680 0.320
670 0.660 0.340
680 0.640 0.360
690 0.620 0.380
700 0.600 0.400
710 0.580 0.420
720 0.560 0.440
730 0.540 0.460
740 0.520 0.480
750 0.500 0.500
760 0.480 0.520
770 0.460 0.540
780 0.440 0.560
800 0.400 0.600
810 0.380 0.620
820 0.360 0.640
830 0.340 0.660
840 0.320 0.680
850 0.300 0.700
860 0.280 0.720
870 0.260 0.740
880 0.240 0.760
890 0.220 0.780
900 0.200 0.800
940 0.120 0.880
990 0.020 0.980
(2) Frequencies above 1000 kHz.
f'kHz K'^1000 K'^1600
1010 0.983 0.017
1020 0.967 0.033
1030 0.950 0.050
1040 0.933 0.067
1050 0.917 0.083
1060 0.900 0.100
1070 0.883 0.117
1080 0.867 0.133
1090 0.850 0.150
1100 0.833 0.167
1110 0.817 0.183
1120 0.800 0.200
1130 0.783 0.217
1140 0.767 0.233
1160 0.733 0.267
1170 0.717 0.283
1180 0.700 0.300
1190 0.683 0.317
1200 0.667 0.333
1210 0.650 0.350
1220 0.633 0.367
1500 0.167 0.833
1510 0.150 0.850
1520 0.133 0.867
1530 0.117 0.883
1540 0.100 0.900
1550 0.083 0.917
1560 0.067 0.933
1570 0.050 0.950
1580 0.033 0.967
[ 28 FR 13574 , Dec. 14, 1963, as amended at 49 FR 43962 , Nov. 1, 1984;
56 FR 64868 , Dec. 12, 1991]
Goto Section: 73.186 | 73.189
Goto Year: 2010 |
2012
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